import java.util.Deque;
import java.util.LinkedList;

public class Queue {
    public static void main(String[] args) {
        //定义队列
        java.util.Queue<Integer> queue = new LinkedList<>();
        //双端对列
        Deque<Integer> dequeu = new LinkedList<>();

        //入队 boolear offer(E e)
        System.out.println(queue.offer(1));
        System.out.println(queue.offer(2));
        System.out.println(queue.offer(3));

        //出队 E poll()
        queue.poll();

        //peek 查看队首元素
        queue.peek();
    }
}
